Interannual variation in phytoplankton blooms and zooplankton productivity and abundance in the Gulf of Maine during Winter

An anomalous winter phytoplankton bloom was observed across the central Gulf of Maine during a winter cruise in late February 1999, but not during a similar mission to the same region in late February 2000. During the cruise in 1999, 0 to 40 m mean chl a concentrations were >2 µg l -1 , while in 2000 total chl a concentrations were 5 µm size fractions were 10 × more abundant in 1999 and included species typically not present in the central Gulf during winter. All developmental stages of planktonic copepods were present, including large numbers of older copepodid stages of species such as Calanus finmarchicus, indicating that the bloom had been proceeding for some time. RNA:DNA ratios of surface C. finmarchicus stage C5 and adult females were at or near maximum temperature-dependent values in 1999, but were considerably reduced in 2000. Egg production rates of C. finmarchicus were high in1999 but reduced in 2000. Both showed a curvilinear relationship with chl a. Analysis of gonads of females of other copepod species indicate similar between-year differ- ences in reproductive rates. We suggest that the presence of the winter bloom in the central Gulf of Maine allows an extra generation of C. finmarchicus and other copepods to develop, leading to a buildup of the population during winter. This will have significant effects on downstream regions such as Georges Bank, which depend on re-supply from the Gulf of Maine.

[1]  M. Wagner,et al.  RNA:DNA ratios as indicators of nutritional condition in the copepod Calanus finmarchicus , 1998 .

[2]  Lynch,et al.  Biological/physical simulations of Calanus finmarchicus population dynamics in the Gulf of Maine , 1998 .

[3]  B. Niehoff.  Gonad morphology and oocyte development in Pseudocalanus spp. in relation to spawning activity , 2003 .

[4]  H. Bigelow.  Plankton Of The Offshore Waters Of The Gulf Of Maine , 1926 .

[5]  Hans-Jürgen Hirche,et al.  A high frequency time series at weathership M, Norwegian Sea, during the 1997 spring bloom: feeding of adult female Calanus finmarchicus , 1998 .

[6]  B. Frost.  A taxonomy of the marine calanoid copepod genus Pseudocalanus , 1989 .

[7]  R. Beardsley,et al.  Springtime nutrient and chlorophyll a concentrations in the southwestern Gulf of Maine , 1995 .

[8]  M. D. Keller,et al.  Spring phytoplankton blooms in the absence of vertical water column stratification , 1992, Nature.

[9]  N. Marcus.  Ecological and evolutionary significance of resting eggs in marine copepods: past, present, and future studies , 1996, Hydrobiologia.

[10]  R. Perry,et al.  Modelling the initiation of spring phytoplankton blooms: a synthesis of physical and biological interannual variability off southwest Nova Scotia, 1983-85 , 1989 .

[11]  M. Ohman,et al.  Sustained fecundity when phytoplankton resources are in short supply: Omnivory by Calanus finmarchicus in the Gulf of St. Lawrence , 1994 .

[12]  M. Ohman,et al.  Density-dependent mortality in an oceanic copepod population , 2001, Nature.

[13]  R. Campbell,et al.  Late fall-early winter recruitment of Calanus finmarchicus on Georges Bank , 1997 .

[14]  P. Holligan,et al.  The influence of physical stability on spring, summer and autumn phytoplankton blooms in the Celtic Sea , 1976, Journal of the Marine Biological Association of the United Kingdom.

[15]  S. Hay,et al.  Calanus finmarchicus egg production and food availability in the Faroe–Shetland Channel and northern North Sea: October–March , 1999 .

[16]  C. Meise,et al.  Spatial and seasonal patterns in abundance and age-composition of Calanus finmarchicus in the Gulf of Maine and on Georges Bank: 1977–1987 , 1996 .

[17]  C. Davis.  Food concentrations on Georges Bank: non-limiting effect on development and survival of laboratory reared Pseudocalanus sp. and Paracalanus parvus (Copepoda: Calanoida) , 1984 .

[18]  D. Harbour,et al.  Copepod hatching success in marine ecosystems with high diatom concentrations , 2002, Nature.

[19]  K. Drinkwater,et al.  Zooplankton distributions at the Georges Bank frontal system: retention or dispersion? , 1993 .

[20]  R. Campbell,et al.  Nucleic acids and growth of Calanus finmarchicus in the laboratory under different food and temperature conditions , 2001 .

[21]  H. Roe,et al.  The diel migrations and distributions within a Mesopelagic community in the North East Atlantic. 1. Introduction and sampling procedures , 1984 .

[22]  Peter C. Smith,et al.  The Mean and Seasonal Circulation off Southwest Nova Scotia , 1983 .

[23]  I. McLAREN,et al.  Life cycles of four species of Pseudocalanus in Nova Scotia , 1989 .

[24]  Daniel R. Lynch,et al.  An adjoint data assimilation approach to diagnosis of physical and biological controls on Pseudocalanus spp. in the Gulf of Maine-Georges bank region , 1998 .

[25]  J. Morski,et al.  COHERENCE IN ZOOPLANKTON OF A LARGE NORTHWEST ATLANTIC ECOSYSTEM , 1983 .

[26]  E. Head,et al.  Distribution of Calanus spp. on and around the Nova Scotia Shelf in April : evidence for an offshore source of Calanus finmarchicus to the central and western regions , 1999 .

[27]  M. Ohman,et al.  On birth and death in the sea , 2002, Hydrobiologia.

[28]  R. Campbell,et al.  Evidence for food limitation of Calanus finmarchicus production rates on the southern flank of Georges Bank during April 1997 , 2001 .

[29]  J. O'Reilly,et al.  Seasonal, horizontal, and vertical distribution of phytoplankton chlorophyll a in the northeast U.S. continental shelf ecosystem , 1998 .

[30]  D. Mountain,et al.  Interannual variability in the copepod populations of Georges Bank and the western Gulf of Maine , 1990 .

[31]  J. Roff.  Community Gradients in the Scotian Shelf Zooplankton , 1983 .

[32]  S. Plourde,et al.  Reproduction of the planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary: relation to the cycle of phytoplankton production and evidence for a Calanus pump , 1993 .

[33]  D. Townsend,et al.  Early spring phytoplankton blooms in the Gulf of Maine , 1986 .

[34]  W. Melle,et al.  Reproduction and development of Calanus finmarchicus, C. glacialis and C. hyperboreus in the Barents Sea , 1998 .

[35]  D. Mountain,et al.  Surface heat flux in the Gulf of Maine , 1996 .

[36]  J. Runge,et al.  The measurement of growth and reproductive rates , 2000 .

[37]  M. Ohman,et al.  A vertical life table approach to zooplankton mortality estimation , 1996 .

[38]  Daniel R. Lynch,et al.  Coupling of an individual-based population dynamic model of Calanus finmarchicus to a circulation model for the Georges Bank region , 1998 .

[39]  R. Campbell,et al.  Growth and development rates of the copepod Calanus finmarchicus reared in the laboratory , 2001 .

[40]  F. Werner,et al.  Upper-ocean transport mechanisms from the Gulf of Maine to Georges Bank, with implications for Calanus supply , 1997 .

[41]  E. Berdalet,et al.  RNA content of copepods as a tool for determining adult growth rates in the field , 1998 .

[42]  G. Hitchcock,et al.  The importance of light in the initiation of the 1972‐1973 winter‐spring diatom bloom in Narragansett Bay1 , 1977 .

[43]  Gordon A. Riley,et al.  Phytoplankton of the North Central Sargasso Sea, 1950–521 , 1957 .

[44]  Martin W. Johnson,et al.  The Biology of the Zooplankton Population in the Bay of Fundy and Gulf of Maine with Special Reference to Production and Distribution. , 1937 .

[45]  X. Irigoien,et al.  A high frequency time series at Weathership M, Norwegian Sea, during the 1997 spring bloom: the reproductive biology of Calanus finmarchicus , 1999 .

[46]  Timothy R. Parsons,et al.  A manual of chemical and biological methods for seawater analysis , 1984 .

[47]  I. McLAREN,et al.  Copepod Production on the Scotian Shelf based on Life-History Analyses and Laboratory Bearings , 1989 .

[48]  H. Sverdrup,et al.  On Conditions for the Vernal Blooming of Phytoplankton , 1953 .

[49]  T. Braarud,et al.  A Quantitative Study of the Phytoplankton in the Bay of Fundy and the Gulf of Maine (including Observations on Hydrography, Chemistry and Turbidity) , 1935 .